New photomultipliers for the KM3NeT project

The KM3NeT project is a future multi-cubic-kilometre scale neutrino telescope in the Mediterranean Sea. The telescope's detection units will be instrumented with optical modules, each housing 31 three-inch photomultiplier tubes (PMTs). Three companies, ET Enterprises, Hamamatsu and MELZ-FEU, develop new types of such PMTs for the KM3NeT project. Hamamatsu has delivered 53 PMTs of R6233MOD type, which will be used to make first fully operated prototypes of the optical modules. The PMTs have been tested at the Erlangen Centre for Astroparticle Physics. These results are presented. The timing parameter ''transit time spread'' (TTS) and the sensitive photocathode area for these PMTs are slightly worse than the KM3NeT specifications. Therefore, Hamamatsu has designed a new 80-mm diameter PMT (R12199) aiming to improve TTS and sensitive area. The delivery of the first samples is expected by the end of December 2011. The new PMTs are tested, and the results are presented.